LTST-C195KGKFKT Dual Color SMD LED Datasheet - Package Dimensions - Green 2.0V Orange 2.0V - 75mW - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a dual-color, surface-mount LED component. The device integrates two distinct light-emitting chips within a single industry-standard package. It is designed for applications requiring indication in two different colors from a compact footprint. The primary advantages of this component include its compatibility with automated assembly processes, high brightness output from advanced semiconductor material, and compliance with environmental regulations. It is suitable for a wide range of consumer electronics, instrumentation panels, and status indication applications where space-saving and reliable performance are critical.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The device has defined limits for safe operation. Exceeding these ratings may cause permanent damage. The maximum power dissipation for each color chip (Green and Orange) is 75 mW at an ambient temperature (Ta) of 25°C. The maximum continuous forward current (DC) is 30 mA per chip. For pulsed operation, a peak forward current of 80 mA is permissible under a 1/10 duty cycle with a 0.1ms pulse width. The maximum reverse voltage that can be applied is 5 V. The operating temperature range is from -30°C to +85°C, while the storage temperature range is wider, from -40°C to +85°C. A derating factor of 0.4 mA/°C applies to the forward current above 25°C, meaning the allowable continuous current decreases as ambient temperature increases to manage thermal load.

2.2 Electrical and Optical Characteristics

Key performance parameters are measured at Ta=25°C and a test current (IF) of 20 mA. The typical forward voltage (VF) for both the Green and Orange chips is 2.0 V, with a maximum of 2.4 V. This low forward voltage is characteristic of AlInGaP technology and contributes to energy efficiency.

Optical Performance:

• Green Chip: Typical luminous intensity is 35.0 mcd (millicandela), with a minimum of 18.0 mcd and a maximum defined by the binning system. Its typical peak emission wavelength (λP) is 574 nm, and the typical dominant wavelength (λd) is 571 nm.
• Orange Chip: Delivers higher typical luminous intensity at 90.0 mcd (minimum 45.0 mcd). It emits at a longer wavelength, with a typical λP of 611 nm and a typical λd of 605 nm.

Both chips share a very wide viewing angle (2θ1/2) of 130 degrees, providing a broad, diffuse light pattern suitable for wide-angle viewing. The spectral line half-width (Δλ) is approximately 15 nm for Green and 17 nm for Orange, indicating relatively pure color emission. Other electrical parameters include a maximum reverse current (IR) of 10 µA at VR=5V and a typical junction capacitance (C) of 40 pF.

3. Binning System Explanation

To ensure consistency in brightness, the LEDs are sorted into bins based on measured luminous intensity at 20 mA. Each bin has a defined minimum and maximum intensity range, with a tolerance of +/-15% applied within each bin.

Green Luminous Intensity Bins:

• Bin M: 18.0 - 28.0 mcd
• Bin N: 28.0 - 45.0 mcd
• Bin P: 45.0 - 71.0 mcd

Orange Luminous Intensity Bins:

• Bin P: 45.0 - 71.0 mcd
• Bin Q: 71.0 - 112.0 mcd
• Bin R: 112.0 - 180.0 mcd
• Bin S: 180.0 - 280.0 mcd

This system allows designers to select components with predictable brightness levels for their application, crucial for achieving uniform appearance in multi-LED arrays.

4. Performance Curve Analysis

The datasheet references typical characteristic curves which are essential for detailed design. While the specific graphs are not reproduced in text, they typically include:

• Relative Luminous Intensity vs. Forward Current: Shows how light output increases with current, typically in a near-linear relationship within the operating range.
• Forward Voltage vs. Forward Current: Illustrates the IV characteristic of the diode junction.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the thermal derating of light output, which generally decreases as temperature rises.
• Spectral Distribution: Graphs showing the relative radiant power versus wavelength for each color, highlighting the peak and dominant wavelengths.

These curves are critical for designing drive circuits, managing thermal performance, and understanding color stability under different operating conditions.

5. Mechanical and Package Information

The device conforms to a standard EIA package outline. Key dimensional notes specify that all dimensions are in millimeters, with a general tolerance of ±0.10 mm unless otherwise stated. The component features a water-clear lens, which allows the native chip color (green or orange) to be seen directly. The pin assignment for the dual-color function is clearly defined: Pins 1 and 3 are for the Green chip, while Pins 2 and 4 are for the Orange chip. This 4-pin configuration allows for independent control of the two colors. The device is supplied packaged in 8mm tape on 7-inch diameter reels, compatible with standard automated pick-and-place equipment.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profiles

Two suggested infrared (IR) reflow profiles are provided: one for normal (tin-lead) solder process and one for lead-free (SnAgCu) solder process. The lead-free profile is mandatory when using lead-free solder paste. The key parameter for infrared soldering is a peak temperature of 260°C sustained for a maximum of 5 seconds. Detailed pre-heat and ramp-up/cool-down rates are typically illustrated in the profile graphs.

6.2 Storage and Handling

LEDs should be stored in an environment not exceeding 30°C and 70% relative humidity. Components removed from their original, moisture-barrier packaging should undergo IR reflow soldering within one week. For longer storage outside the original pack, they must be kept in a sealed container with desiccant or in a nitrogen atmosphere. If stored unpackaged for more than a week, a bake-out at approximately 60°C for at least 24 hours is required before assembly to remove absorbed moisture and prevent "popcorning" during reflow.

6.3 Cleaning

If cleaning after soldering is necessary, only specified solvents should be used. Unspecified chemicals may damage the plastic package. Acceptable methods include immersion in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute.

7. Packaging and Ordering Information

The standard packaging is a 7-inch reel containing 4000 pieces. A minimum order quantity of 500 pieces is available for remainder quantities. The tape-and-reel system conforms to ANSI/EIA 481-1-A-1994 specifications. Empty pockets in the carrier tape are sealed with a top cover tape. Quality specifications allow for a maximum of two consecutive missing components on a reel. The part number LTST-C195KGKFKT follows the manufacturer's internal coding system, identifying the specific dual-color variant.

8. Application Recommendations and Design Considerations

8.1 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness when driving multiple LEDs in parallel, it is strongly recommended to use a current-limiting resistor in series with each individual LED (Circuit Model A). Driving multiple LEDs in parallel directly from a single current source (Circuit Model B) is not recommended, as slight variations in the forward voltage (Vf) characteristics between individual LEDs will cause significant differences in current sharing and, consequently, brightness.

8.2 Electrostatic Discharge (ESD) Protection

The device is sensitive to electrostatic discharge. ESD damage can manifest as high reverse leakage current, low forward voltage, or failure to illuminate at low currents. Preventive measures must be implemented during handling and assembly:

• Use conductive wrist straps or anti-static gloves.
• Ensure all equipment, workstations, and storage racks are properly grounded.
• Use an ionizer to neutralize static charge that may accumulate on the LED lens due to handling friction.

8.3 Application Scope and Cautions

This component is intended for general-purpose electronic equipment. For applications requiring exceptional reliability where failure could risk life or health (e.g., aviation, medical devices, safety systems), consultation with the component manufacturer is required prior to design-in. Designers must adhere strictly to the Absolute Maximum Ratings and recommended operating conditions outlined in this datasheet.

9. Technical Comparison and Differentiation

The key differentiating features of this component are its dual-color capability in a single SMD package and the use of AlInGaP semiconductor technology. AlInGaP (Aluminum Indium Gallium Phosphide) is known for providing high luminous efficiency and excellent color purity, particularly in the amber-to-red spectrum, compared to older technologies. The integration of two chips saves board space and simplifies assembly compared to using two separate single-color LEDs. The wide 130-degree viewing angle is another advantage for applications requiring broad visibility.

10. Frequently Asked Questions (FAQ)

Q: Can I drive both the Green and Orange chips simultaneously at their maximum DC current of 30mA each?
A: Yes, but the total power dissipation must be considered. Simultaneous operation at 30mA each would result in a combined power dissipation that approaches the individual limits. Careful thermal management of the PCB is advised in such a use case.

Q: What is the difference between peak wavelength (λP) and dominant wavelength (λd)?
A: Peak wavelength is the wavelength at which the emission spectrum has its highest intensity. Dominant wavelength is derived from the CIE chromaticity diagram and represents the single wavelength of a pure monochromatic light that would be perceived by the human eye as having the same color as the LED's output. λd is often more relevant for color specification.

Q: How do I select the correct bin for my application?
A: Choose a bin based on the minimum brightness required for your design under worst-case conditions (e.g., maximum operating temperature, end-of-life). Using a bin with a higher minimum intensity provides a brightness safety margin. For consistent appearance across multiple units, specify a single bin code.

11. Practical Design and Usage Examples

Example 1: Dual-State Status Indicator: A single LTST-C195KGKFKT can replace two separate LEDs to indicate two different system states (e.g., Green for "Ready/Normal" and Orange for "Standby/Warning"). This saves PCB area and reduces part count. The drive circuit would consist of two independent current-limiting resistor networks connected to the appropriate pins (1/3 for Green, 2/4 for Orange), controlled by microcontroller GPIO pins.

Example 2: Battery Level Indicator in a Compact Device: In a handheld device, multiple dual-color LEDs could be used in a bar-graph style. Different colors could indicate different battery level thresholds (e.g., Green for >50%, Orange for 20-50%, and both off for <20%). The wide viewing angle ensures the indicator is visible from various angles.

12. Operating Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light when an electric current passes through them. This phenomenon, called electroluminescence, occurs when electrons recombine with electron holes within the device, releasing energy in the form of photons. The specific material of the semiconductor chip determines the color (wavelength) of the emitted light. The AlInGaP material system used in this component is particularly efficient at converting electrical energy into visible light in the green-to-red portion of the spectrum. The dual-color package contains two electrically isolated semiconductor chips, each made of material tuned to emit a specific color, housed under a common water-clear epoxy lens.

13. Technology Trends and Developments

The general trend in SMD LED technology continues towards higher efficiency (more lumens per watt), improved color rendering, and increased power density in smaller packages. There is also a strong drive for broader adoption of lead-free and RoHS-compliant materials and processes across the electronics industry, which this component supports. The integration of multiple functions (like dual-color or RGB) into single packages addresses the demand for miniaturization and design simplicity in modern electronics. Advances in phosphor technology and chip design continue to push the boundaries of brightness and color stability over temperature and lifetime.